The process of gastrulation is essential to the establishment of axial pattern in vertebrate embryos Though the morphogenetic movements of gastrulation in amphibians have been very extensively described, the regulation of these movements at the molecular level has yet to be thoroughly investigated in any vertebrate. The way in which genetic pathways involved in axial patterning initiate morphogenetic movements and how these movements subsequently affect the activity of other downstream genetic pathways has also been neglected. Understanding the interaction of genetic pathways and morphogenetic movements will be of critical importance in building a comprehensive understanding of embryonic pattern formation. Such basic investigations of developmental mechanisms form the foundation of birth defects research, and the study of cell movement and morphogenesis in early development will also yield clues to understanding the mechanisms of cell movement and morphogenesis in general (for example, metastasis, wound healing, etc.). In order to better understand how complex cell behaviors are coordinated during early development, the molecules involved in the regulation and execution of convergent extension movements during Xenopus gastrulation will be examined in detail. As this morphogenetic behavior has been exhaustively described at the cell and tissue level, it is a perfect candidate for investigation at the molecular level. This investigation will utilize two key approaches. First, the activity of previously identified molecules involved in axial patterning will be examined in explants and whole embryos specifically for their effects on convergent extension. And second, subtractive hybridization and a functional screen will be utilized to identify novel genes involved in convergent extension, and interesting molecules and their roles in morphogenesis and axial patterning will be examined in detail. This approach should identify novel molecules both of structural and regulatory function, as well as define new roles for previously described molecules in the coordination of morphogenetic movements.